Bromine water reacts with SO2 to form

Bromine water reacts with SO2 to form

Bromine react with sulphur dioxide and water to produce hydrogen bromide and sulfuric acid

SO2+Br2+H2O→HBr+H2SO4

There are two bromines on the left, so we need 2 HBr's on the right to balance bromine. Then there are 4 hydrogens on the right, so we need 2 H2O's on the left. After that's done, everything is balanced, and you're left with the correct answer: